From publisher blurb:
MasterBook is a universal roleplaying system. Flexible and easy to learn, the rules can be adapted to everything from science fiction to high fantasy, from pulp adventures to dark horror. Add the critically-acclaimed MasterDeck cards to enhance the action with more excitement and more drama, and your imagination is the only limit.
MasterBook EZ is the streamlined version of MasterBook, serving as an introduction to the mechanics. It is fully functional and ready to run, but like any lite version of a game, the mechanics have been distilled to their most-basic components for simpler and faster play. Two 10-sided dice are required. Once comfortable with MasterBook EZ, keep using it or step up to MasterBook for the full experience.
If you've never tried MasterBook, this will be the perfect starting point. If you have, this may also be the lighter version you have been seeking for times when you just want to run a quick and easy game.